CN109937479B - Lead frame material, method for manufacturing the same, and semiconductor package - Google Patents

Abstract

The present invention provides a lead frame material (10), which has: a conductive base (1), and protrusions ( 4) A roughened film (3) of at least one roughened layer (2) is formed, and the protrusions (4) have the following shape: The maximum width is 1 to 5 times the minimum width when measured at the lower portion located closer to the conductive substrate (1) side than the measurement position of the maximum width.

Description

Lead frame material, manufacturing method thereof, and semiconductor package

technical field

The present invention relates to a lead frame material suitable for a resin-sealed type semiconductor device, a manufacturing method thereof, and a semiconductor package by electrically connecting a semiconductor element and a lead frame having a surface-treated layer to each other and encapsulating it with a molding resin. It is sealed and formed.

Background technique

Such a resin-sealed semiconductor device has a structure in which a semiconductor element and a lead frame electrically connected to each other by wires or the like are sealed with a molding resin. Such a resin-encapsulated semiconductor device is generally produced by subjecting a lead frame to surface treatment such as external plating to form a surface coating with a Sn alloy such as a Sn—Pb alloy or a Sn—Bi alloy.

In recent years, in order to simplify the assembly process and reduce costs, lead frames (pre-plated frames, Pre-Plated Frame) have begun to be used, that is, the surface of the lead frame is preliminarily applied to the surface of the lead frame to improve the Solder wettability plating (for example, Ni/Pd/Au) (for example, see Patent Document 1).

On the other hand, in order to improve the adhesion between the lead frame and molding resin in a resin-sealed semiconductor device, a technique of roughening the plating surface of the lead frame has been proposed (for example, see Patent Document 2).

Technology for roughening the plated surface Roughening the surface by applying roughening plating to the lead frame can expect: (1) The effect that the molding resin enters the unevenness of the roughened plating film and forms a strong mechanical bond ( anchoring effect), (2) improvement in chemical bonding due to improvement in the contact area between the molding resin and the plated surface, and the like.

By roughening the surface of the lead frame, the adhesion between the mold resin and the lead frame is improved, and peeling between the lead frame and the mold resin is suppressed, and as a result, the reliability of the resin-sealed semiconductor device can be improved.

prior art literature

patent documents

Patent Document 1: Japanese Patent Application Laid-Open No. 4-115558

Patent Document 2: Japanese Patent Application Laid-Open No. 6-029439

Contents of the invention

The problem to be solved by the present invention

By roughening the surface of the lead frame, it is possible to surely improve the adhesion of the mold resin to the lead frame compared with conventional resin-sealed semiconductor devices. However, in recent years, the level required for reliability has become more stringent than before, so even high-temperature and high-humidity durability tests are required, such as harsh conditions of 168 hours in an environment with a temperature of 85°C and a humidity of 85%. Under the condition of high temperature and high humidity test, it must also meet the pass standard of reliability. On the other hand, in the conventional configuration in which only the surface of the lead frame is roughened as in Patent Document 1, a gap may be generated between the resin and the lead frame, and the acceptable standard for reliability may not be satisfied. This is considered to be because, as a resin-sealed semiconductor device, in recent years, based on the use of packages such as QFN (Quad Flat Non-Leaded Package) type and SOP (Small Outline Package) type, etc. As the number increases, the level required for the adhesiveness of the resin to the lead frame is further increased. Therefore, in the resin-sealed semiconductor device, the adhesiveness of the resin to the lead frame is required to maintain good adhesiveness even under the severe conditions as described above, and further improvement is required.

The object of the present invention is to provide a lead frame material suitable for forming a high-temperature and high-humidity test under severe conditions as described above, a method of manufacturing the same, and a semiconductor package with high reliability. A lead frame surface that maintains good resin adhesion.

means of solving problems

The inventors of the present invention conducted extensive studies to solve the above problems. Considering that the cross-sectional shape of the protrusions of the roughened particles constituting the roughened layer of the roughened coating formed on the conductive substrate greatly affects the resin adhesion, It was investigated whether the good adhesion due to the anchoring effect, which is the uneven surface caused by the protrusions formed on the surface of the lead frame material, can be maintained even when the high temperature and high humidity test is carried out under the above severe conditions. (Especially in recesses) are filled with forming resin.

The inventors of the present invention have found that by controlling the protrusions constituting the roughened layer of the roughened film formed on the conductive substrate to have the following shape: the maximum The width is 1 to 5 times the minimum width when measured at the lower part of the conductive substrate side than the maximum width measurement position, so that the minimum width of the protrusions of the roughened particles can be effectively Controls the peeling phenomenon caused by resin shearing, which tends to occur due to stress concentration caused by expansion and contraction of resin. As a result, it was found that the good adhesion due to the anchoring effect can be maximized through the roughened layer, and by controlling the protrusions forming the roughened layer to the above-mentioned shape, even under high temperature and high humidity, which cannot normally be tolerated, Durability test, such as high temperature and high humidity test under severe conditions of temperature 85°C and humidity 85% for 168 hours, can also maintain good adhesion of the resin to the lead frame.

That is, the main configuration of the present invention is as follows.

(1) A lead frame material having:

conductive substrate, and

a roughened film comprising at least one roughened layer formed by a plurality of protrusions of roughened particles directly or via an intermediate layer on at least one side of the conductive substrate,

The protrusions have a shape in which the maximum width when measured on a cross-section in the thickness direction of the roughened film is measured relative to a lower portion located closer to the conductive substrate side than the measurement position of the maximum width. The minimum width is 1 to 5 times.

(2) The lead frame material described in (1) above, wherein the conductive base is copper, copper alloy, iron, iron alloy, aluminum or aluminum alloy.

(3) The lead frame material described in (1) or (2) above, wherein the roughened layer comprises copper, copper alloy, nickel, nickel alloy, palladium, palladium alloy, silver, silver alloy, tin, tin metals or alloys in alloys, zinc, zinc alloys, rhodium, rhodium alloys, ruthenium, ruthenium alloys, iridium, and iridium alloys.

(4) The lead frame material according to any one of (1) to (3) above, which further has a surface coating film including at least one surface coating layer on at least a part of the surface of the roughened coating film, The surface coating layer comprises a metal or alloy selected from palladium, palladium alloy, rhodium, rhodium alloy, ruthenium, ruthenium alloy, platinum, platinum alloy, iridium, iridium alloy, gold, gold alloy, silver and silver alloy.

(5) The lead frame material as described in (4) above, wherein the intermediate layer is nickel, nickel alloy, cobalt, cobalt alloy, copper or copper alloy.

(6) A method of manufacturing a lead frame material, comprising the step of forming a roughened coating, the roughened coating comprising forming a plurality of roughened particles on at least one surface of a conductive substrate by electroplating directly or via an intermediate layer. At least one roughened layer formed by protrusions; the protrusions have the following shape: the maximum width when measured in the thickness direction section of the roughened film is relative to the position located closer to the measurement position than the maximum width The minimum width at the time of measurement of the lower portion on the side of the conductive substrate is 1 to 5 times.

(7) A semiconductor package comprising the lead frame material according to any one of (1) to (5) above.

The effect of the invention

The lead frame material of the present invention comprises a conductive substrate, and a roughened coating comprising at least one roughened layer formed by protrusions of a plurality of roughened particles directly or via an intermediate layer on at least one side of the conductive substrate. film, and the protrusions have a maximum width when measured in the thickness direction cross-section of the roughened film relative to the measurement position on the lower side of the conductive substrate side closer to the measurement position of the maximum width. A shape with a minimum width of 1 to 5 times, so that even when performing a high-temperature and high-humidity durability test, such as a high-temperature and high-humidity test in an environment with a temperature of 85°C and a humidity of 85% for 168 hours, the The lead frame maintains good resin adhesion, and the adhesion hardly deteriorates, and a semiconductor package composed of the lead frame material can realize high reliability.

Description of drawings

FIG. 1 is a schematic cross-sectional view of a representative leadframe material according to the present invention.

FIG. 2 is a diagram for explaining a method of calculating a specific surface area of a roughened layer.

Fig. 3 is a diagram for explaining the maximum width Wmax and the minimum width Wmin of protrusions constituting one roughening layer.

Fig. 4 is a schematic cross-sectional view of other lead frame materials according to the present invention.

FIG. 5 is a diagram for explaining the maximum width Wmax and the minimum width Wmin of protrusions constituting two roughening layers.

detailed description

Next, the lead frame material according to the present invention will be described below with reference to the drawings, with reference to specific examples of embodiments. Fig. 1 shows a schematic cross-section of a representative lead frame material according to the present invention, reference numeral 1 in Fig. 1 is a conductive substrate, 2 is a roughened layer, 3 is a roughened coating, 4 is a protrusion, And 10 is the lead frame material. The lead frame material 10 of the present invention includes a conductive substrate 1 and a roughened coating 3 including at least one roughened layer 2 .

(conductive substrate)

The conductive substrate 1 may be any material as long as it has conductivity, for example, copper, copper alloy, iron, iron alloy, aluminum or aluminum alloy, etc., preferably copper alloy, iron alloy or aluminum alloy. As a lead frame material, it is particularly preferable to use a copper alloy having a good balance between electrical conductivity and strength because strength capable of withstanding deformation such as bending processing is required when bonding to a semiconductor element. Among them, as copper alloys, for example, alloys listed in CDA (Copper Development Association), that is, "C14410 (Cu-0.15Sn, manufactured by Furukawa Electric Co., Ltd., trade name: EFTEC (registered trademark)- 3)", "C19400 (Cu-Fe alloy material, Cu-2.3Fe-0.03P-0.15Zn)", "C18045 (Cu-0.3Cr-0.25Sn-0.2Zn, manufactured by Furukawa Electric Co., Ltd., commercial Name: EFTEC (registered trademark)-64T), "C50710 (Cu-2.0Sn-0.2Ni-0.05P), manufactured by Furukawa Electric Industry Co., Ltd., trade name: MF202", "C70250 (Cu-3Ni-0.65Si- 0.15Mg), manufactured by Furukawa Electric Industry Co., Ltd., trade name: EFTEC (registered trademark)-7025" and the like. It should be noted that the units of the numbers immediately before each element are "mass %". It is preferable to use such Like a copper alloy, a strip of a copper alloy with a tensile strength of 350-800 N/mm ² , preferably 500-800 N/mm ² , and an electrical conductivity of 30-90% IACS, preferably 50-80% IACS. The above "% "IACS" indicates the electrical conductivity when the resistivity of International Annealed Copper Standard (International Annealed Copper Standard) 1.7241×10-8Ωm is set as 100% IACS, for example, the electrical conductivity of "50% IACS" indicates the electrical conductivity of international standard annealed copper 50% of.

Moreover, in the case of an iron alloy, a 42 alloy (Fe-42 mass %Ni), stainless steel, etc. are mentioned, for example. The conductive base 1 containing such an iron alloy does not have such a high conductivity, but it can be applied to a lead frame material 10 that does not need to have such a high conductivity and is intended to transmit electrical signals.

Moreover, in the case of an aluminum alloy, Al-Mg alloys, such as A5052, are mentioned, for example.

In resin-sealed semiconductor devices, since heat tends to accumulate inside through the molding resin, it becomes important to release the internal heat along the conductive substrate. In the present invention, by forming a rough coating on the surface of the conductive substrate, the thickness of the conductive substrate can be reduced to 0.05 mm while improving the heat dissipation effect compared to the case where no rough coating is formed. If the thickness of the conductive base is thinner than 0.05 mm, sufficient heat dissipation cannot be obtained, and if the thickness of the conductive base is more than 2 mm, the miniaturization of the semiconductor device cannot be achieved. Therefore, the thickness of the conductive substrate 1 is preferably 0.05 to 2 mm, more preferably 0.1 to 1 mm.

(rough coating)

The rough coating 3 is composed of at least one rough layer 2 formed of a plurality of protrusions 4 of rough particles on at least one surface of the conductive substrate 1 directly or via an intermediate layer (not shown).

In addition, the rough coating 3 only needs to be composed of at least one rough layer 2 , but it is preferably composed of 1 to 3 rough layers 2 in consideration of the complexity of the manufacturing process and the like. In terms of the method of forming the rough film 3, one or more factors among the composition, the formation conditions, etc. It is more preferable to form the so-called multiple roughening of the second layer of roughening layer 2-2 different from one layer of roughening layer 2-1, which can effectively increase the specific surface area with a thinner film thickness (see FIG. 4 ). It should be noted that, in the present invention, the film thickness of the roughened film 3 is not measured locally, but by at least the film thickness of the fluorescent X-ray method (for example, such as SFT 9400 (trade name) manufactured by SII Corporation, etc. Measuring device) is represented by the average film thickness measured at any three points with a collimator diameter of 0.2 mm or more. In addition, when the rough coating 3 is composed of a plurality of rough layers 2 , the total thickness of all the layers is defined as the thickness of the rough coating 3 .

In addition, the film thickness of the roughened film 3 is not particularly limited, but the larger the film thickness, the larger the unevenness caused by the roughening tends to become. Therefore, in order to increase the roughened shape, the lower limit value of the film thickness of the roughened film 3 is preferably 0.2 μm or more, more preferably 0.5 μm or more, and still more preferably 0.8 μm or more. On the other hand, when the thickness of the roughened coating 3 exceeds 3 μm, the roughened coating 3 falls off during transportation, and so-called “dust falling” may increase. Therefore, the upper limit of the film thickness of the roughened film 3 is preferably 3 μm or less, more preferably 2 μm or less, and still more preferably 1.5 μm or less.

[coarsening layer]

The roughened layer 2 is formed by a plurality of protrusions 4 of roughened particles.

Various methods, such as wet plating and dry plating, can be mentioned as a method of forming the roughening layer 2, However, Forming by electroplating is especially preferable from a viewpoint, such as being able to form easily and cheaply.

The roughening layer 2 preferably comprises, for example, copper, copper alloys, nickel, nickel alloys, palladium, palladium alloys, silver, silver alloys, tin, tin alloys, zinc, zinc alloys, rhodium, rhodium alloys, ruthenium, ruthenium alloys, iridium and metals or alloys in iridium alloys. From the viewpoint of improving the adhesion to the surface coating, especially when a surface coating (not shown) described later is further formed on the roughening coating 3, it is more preferable that the roughening layer 2 contains copper, a copper alloy, Nickel or nickel alloys. Copper alloys include copper-tin alloys and copper-zinc alloys, and examples of nickel alloys include nickel-zinc alloys and nickel-tin alloys.

And, the main feature of the structure of the present invention is to realize the rationalization of the cross-sectional shape of the protrusions 4 of the roughened particles constituting the roughened layer 2, more specifically, as shown in FIG. 3, control the protrusions 4 so that The maximum width Wmax when measured on a cross-section in the thickness direction of the roughened coating 3 is 1 to 5 with respect to the minimum width Wmin when measured at a lower portion of the conductive substrate 1 side than the measurement position of the maximum width Wmax. double shape.

This is the result of intensive research by the present inventors, that is, if a roughened layer is formed with the same surface roughness, the shear strength (adhesion strength) of the resin in the shear test is high, and good resin adhesion is obtained, but After a high-temperature and high-humidity durability test, such as a high-temperature and high-humidity test under harsh conditions of 85°C and 85% humidity for 168 hours, the roughened layer with the same surface roughness has shear strength. Greatly reduce the situation where good resin adhesion cannot be maintained. As a result of further research on this point, it was found that the cross-sectional shape of the protrusions of the roughened particles forming the roughened layer is greatly affected, especially at the position where the width of the protrusions is the smallest, stress concentration caused by thermal expansion and contraction of the resin, dense Compatibility is reduced.

For this reason, the present inventors conducted further detailed studies and found that the ratio of the maximum width to the minimum width of the roughened particles forming the roughened layer of the roughened coating is controlled to be 1 to 5, that is, the protrusions are controlled so as to have The shape in which the maximum width when measured on a cross-section in the thickness direction of the roughened film is 1 to 5 times the minimum width when measured at the lower portion of the conductive substrate side than the measurement position of the maximum width, thereby , in a roughened layer having the same degree of surface roughness, even after performing a high-temperature and high-humidity durability test, for example, a high-temperature and high-humidity test under severe conditions of standing in an environment of a temperature of 85°C and a humidity of 85% for 168 hours, Good resin adhesion can also be maintained with little decrease in the shear strength (adhesive strength) of the resin.

In the protrusion, the fact that the maximum width is twice the minimum width means that the maximum width and the minimum width are the same, and examples of the shape of the protrusion include a substantially columnar shape or a prism shape. On the other hand, if the maximum width of the protrusion exceeds 5 times the minimum width, the anchoring effect cannot be effective due to increased stress concentration caused by expansion or contraction of the resin at the position of the minimum width of the protrusion forming the roughened layer. Play, resulting in the position of the minimum width of the protrusion becomes easy to break. Therefore, the maximum width of the protrusion is 1 to 5 times the minimum width. In addition, not only the molded resin exerts the anchoring effect, but also makes it difficult for the resin to crack at the position of the smallest portion of the protrusion forming the roughened layer. Therefore, for the lead frame material, it is necessary not only to improve the shear strength, but also to vertically In the case where the tensile strength in the direction also needs to be further improved, the ratio of the maximum width to the minimum width of the protrusion is preferably 1.1 to 4.9 times, more preferably 1.2 to 4.8 times, further preferably 1.5 to 4.0 times, and most preferably 1.5 times to 3.0 times. It should be noted that the shape of the surface of the protrusion may be sharp or rounded, and the ratio of the maximum width to the minimum width of the protrusion is important.

<Definition of maximum width and minimum width of protrusions>

In terms of the maximum and minimum widths of the protrusions in the present invention, vertical cross-section specimens are manufactured by processing lead frame materials with roughened layers formed by methods such as focused ion beam (FIB), mechanical grinding, etc., Next, for the roughened layer of the vertical cross-section sample, use an optical microscope, scanning electron microscope, etc. to observe the cross-section, and move the line segment in parallel from the surface of the conductive substrate to the surface of the roughened layer. For the plurality of protrusions forming the roughened layer For each protrusion, the width is measured to determine the maximum value (maximum width) Wmax and the minimum value (minimum width) Wmin. A more detailed description is carried out as follows. As shown in FIG. 3, a perpendicular line is drawn from the direction of the conductive substrate 1 to the roughened layer, and a line (parallel line) parallel to the substrate is scanned from its apex toward the direction of the conductive substrate 1. At this time, the width representing the maximum value of the protrusion 4 is determined as the maximum width, which is set as Wmax, and further scanning parallel lines in the direction from the position of the maximum width Wmax toward the conductive substrate 1, and the width representing the protrusion 4 at this time is The width of the minimum value of 4 is determined as the minimum width and is set to Wmin. Therefore, in the present invention, the value of the ratio Wmax/Wmin must be 1-5.

It should be noted that the minimum width Wmin of the protrusions 4 refers to the measurement at the lower portion of the conductive substrate 1 side from the measurement position of the maximum width Wmax of the protrusions 4 when measured in the thickness direction cross-section of the roughened film 3. When the minimum width Wmin. This is based on the knowledge that the shear strength is determined by the width of the lower portion (bottom end portion) of the protrusion 4 on the conductive substrate 1 side in the shear test. In addition, in order to observe an arbitrary cross section, the protrusion 4 was observed at each position of the roughening layer 2. This is because the roughened layer 2 is usually basically formed three-dimensionally. Therefore, as the roughened layer 2 for measuring the maximum width Wmax and the minimum width Wmin of the protrusions 4, the situation of one roughened layer 2, as shown in FIG. 5 shows two or more roughened layers (for example, two roughened layers 2-1 and 2-2 in FIG. In addition to this, for example, there are two or more roughened layers and the outline of the outermost surface of the roughened film 3 is not clear, and the roughened layer 2 appears to be raised from the conductive substrate 1. In the present invention, it is regarded as a roughened layer that cannot be measured. By these methods, at any cross section, for 10 protrusions 4 present in one roughening layer 2, the respective maximum width Wmax and minimum width Wmin are measured, and the ratio Wmax/Wmin of the maximum width Wmax to the minimum width Wmin is calculated , the lead frame material 10 having the roughened layer 2 whose average value of these ratios is 1 to 5 times is defined as the lead frame material of the present invention.

<Regarding the minimum width of protrusions and the interval between protrusions>

In addition, the size of the minimum width Wmin of the protrusions 4 forming the roughened layer 2 is not particularly specified in the present invention, but when the minimum width Wmin is too small, it is difficult for the resin to exist in the gap between the protrusions 4 and 4 of the roughened layer 2. tends to flow, and when the minimum width Wmin is too large, the effect of increasing the shear strength tends to be small. Therefore, the minimum width Wmin of the protrusions 4 is preferably in the range of 0.2 μm to 3 μm on average, more preferably in the range of 0.5 μm to 1 μm. In addition, the distance between the protrusions 4 and 4 is not particularly limited, but the average distance between the tops of the protrusions 4 and 4 is preferably in the range of 0.2 to 20 μm, more preferably in the range of 0.5 μm to 10 μm.

<About specific surface area of roughened layer>

The lead frame material 10 of the present invention first has a roughened layer 2 relative to a conductive base (hereinafter also simply referred to as “base”) 1 . The specific surface area of the roughened layer 2 is preferably 110% or more. This is because if the specific surface area is less than 110%, the anchoring effect cannot be sufficiently obtained. The upper limit of the specific surface area is not particularly limited, but if the specific surface area is too large, the roughened unevenness becomes too large and the roughened layer tends to fall off, so the specific surface area is preferably 500% or less.

It should be noted that, as a method of calculating the specific surface area, as shown in FIG. Indicated by the dotted line A) divided by the surface (straight line) length of the conductive substrate 1 (the thick solid line B in FIG. Measurements are performed using a measuring device such as a microscope (for example, manufactured by Bruker AXS). In addition, in the present invention, the formation position of the roughened layer only needs to be formed in at least a part of the resin molded portion, and it goes without saying that the entire surface may be processed, or the roughened layer 2 may be partially formed. In addition, for example, it is preferably formed in at least 1/5 or more, more preferably 1/2 or more of the area of the resin-molded portion of the lead frame material 10 , thereby exhibiting an effect of improving adhesion. Most preferably, the roughened layer 2 is formed on the entire surface of the resin molding. As the shape of the roughened layer 2 provided in this portion, various forms such as stripe shape, dot shape, and ring shape can be adopted. In addition, in the case of resin molding only one side, for example, the roughened layer 2 may be formed only on one side.

(middle layer)

In addition, in the lead frame material 10 of the present invention, an intermediate layer may be formed between the conductive base 1 and the roughened film 3, and the intermediate layer is used, for example, to suppress diffusion of components constituting the conductive base 1 and to improve adhesion. . Examples of the intermediate layer include nickel, nickel alloy, cobalt, cobalt alloy, copper or copper alloy.

(surface coating)

In addition, the lead frame material 10 of the present invention preferably further includes a surface coating on at least a part of the surface of the roughened coating 3 directly or through an intermediate layer, and the surface coating includes at least one surface coating layer, and the surface coating layer is preferably Contains a metal or alloy selected from the group consisting of palladium, palladium alloys, rhodium, rhodium alloys, ruthenium, ruthenium alloys, platinum, platinum alloys, iridium, iridium alloys, gold, gold alloys, silver and silver alloys.

[surface coating]

As various alloys constituting the surface coating layer, for example, a palladium-silver alloy as a palladium alloy, a rhodium-palladium alloy as a rhodium alloy, a ruthenium-iridium alloy as a ruthenium alloy, a platinum-gold alloy as a platinum alloy, Platinum-iridium alloy as an iridium alloy, gold-silver alloy as a gold alloy, silver-tin alloy as a silver alloy, and the like. One type of surface coating may be used, but two or more layers are preferable. Typical layer structures in the case of two or more surface coating layers constituting the surface coating include Pd/Au, Rh/Au, Pd/Ag/Au, Pd/Rh/Au, Ru/Pd/Au, etc. By forming the surface coating layer on the rough coating as described above, the heat resistance of the lead frame to heat generation can be improved, and at the same time, the strength of the protrusions of the roughened particles forming the rough layer of the rough coating can be improved, Preventing the breakage of protrusions can further exert the anchoring effect. In addition, from the viewpoint of improving the adhesion to the surface coating, it is more preferable that the roughening layer is two layers of copper and nickel and the surface coating layer is a Pd/Au2 layer or Rh/Au2 layer, and it is more preferable that the roughening layer is The layer structure is 2 layers of copper on the lower side rough layer and nickel on the upper side rough layer, and the layer structure of the surface coating layer is 2 layers of Pd on the lower surface coating layer and Au on the upper side surface coating layer Alternatively, the lower surface coating layer is Rh and the upper surface coating layer is two layers of Au.

If the film thickness of these surface coating layers is too thick, the surface irregularities of the roughened coating 3 may be buried, and the above-mentioned effects of the present invention may not be fully exhibited, and the surface coating is mainly composed of a noble metal material, which may result in an increase in cost. Therefore, the film thickness of each surface coating layer is preferably 1 μm or less, more preferably 0.03 μm or less, in terms of the total film thickness of the laminated surface coating layers (film thickness of the surface coating film).

(About the manufacturing method of lead frame material)

Next, the manufacturing method of the lead frame material 10 of this invention is demonstrated.

A conductive substrate 1 is prepared, and the conductive substrate 1 is subjected to a cathodic electrolytic degreasing step and a pickling step. Next, as required, an intermediate layer is formed by electroplating, and then a rough coating 3 comprising at least one rough layer 2 is formed by electroplating, and then further as required, by electroplating, a surface coating 3 comprising at least one surface coating layer is formed. film, from which the lead frame material 10 can be manufactured. As representative examples of specific manufacturing conditions, cathodic electrolytic degreasing conditions are shown in Table 1, pickling conditions are shown in Table 2, various intermediate layer formation conditions are shown in Table 3, and various roughening conditions are shown in Table 4. The formation conditions of layer 2, Table 5 shows the formation conditions of various surface coating layers. In the manufacturing method of the lead frame material 10 mentioned above, the case where the intermediate|middle layer, the roughening layer 2, and the surface coating layer are all manufactured by electroplating was exemplified. Since the shape of the protrusions can be controlled relatively easily by current density, stirring, temperature, treatment time, etc. and the operation is simple and convenient, it is preferable to form the roughened layer 2 by electroplating. From a viewpoint, it is also preferable to form by a wet plating method such as an electroplating method, but it can also be produced by a dry plating method or other manufacturing methods, and is not particularly limited.

[Table 1]

Table 1. Cathodic electrolytic degreasing conditions

[Table 2]

Table 2. Pickling conditions

[table 3]

Table 3. Formation conditions of various intermediate layers

[Table 4]

Table 4. Formation conditions of various roughening layers

[table 5]

Table 5. Conditions for forming various surface coating layers

Example

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited by these examples.

Various conductive substrates shown in Table 6 were prepared in advance and cut into 40 mm×40 mm test piece size with a plate thickness of 0.2 mm, and were subjected to cathodic electrolytic degreasing under the conditions shown in Table 1 above. Next, after pickling the conductive substrate under the conditions shown in Table 2, at least one roughened layer was formed on the surface of the conductive substrate with the layer structure shown in Table 6 to obtain a test piece of the lead frame material. It should be noted that, in the formation of the roughened layer, not only the specific surface area but also the ratio of the maximum width to the minimum width of the protrusions of the roughened layer in the cross section are controlled. In Examples 1 to 30, in Examples 11 to 13, in addition to the lower roughened layer, the roughened coating further forms an upper roughened layer, thereby consisting of two roughened layers. In Examples 22 to 24, an intermediate layer was further formed between the conductive substrate and the roughened coating, and for Examples 29 and 30, the roughened coating also formed an upper roughened layer in addition to the lower roughened layer, thereby resulting in A two-layer roughening layer is formed, and a two-layer surface coating including a lower surface coating layer and an upper surface coating layer is further formed. As a reference, in Comparative Example 1, although the specific surface area of the roughened layer is very large, being 550%, the ratio of the maximum width to the minimum width of the protrusions forming the roughened layer is not controlled, so the production in the present invention Test pieces for lead frame materials outside the range (5.2 times).

For the above-mentioned test piece, a transfer molding tester (product name: Model FTS) manufactured by Kohtaki Seiki Co., Ltd. was used under the conditions of a mold temperature of 130° C., a holding time of 90 seconds after molding, and an injection pressure of 6.865 MPa. The molding resin was injected down and molded to form a pudding-shaped test piece with a contact area of 10 mm ² . Each test piece was subjected to a high-temperature and high-humidity test (maintained at 85° C., 85% RH for 168 hours), and resin adhesion and powder falling properties were evaluated for each test piece under the following conditions. The evaluation results are shown in Table 7.

(Resin Adhesion Evaluation)

Evaluation resin: G630L, manufactured by Sumitomo Bakelite Co., Ltd. (trade name)

Evaluation conditions: Device: 4000Plus, manufactured by Nordson Advanced Technology Co., Ltd. (trade name),

Load Cell: 50kg

Measuring range: 10kg

Test speed: 100μm/s

Test height: 10μm

Table 7 shows the evaluation results of resin adhesiveness. It should be noted that in the evaluation of the resin adhesiveness shown in Table 7, when the shear strength (peel strength) is 9.8 MPa or more on average, the resin adhesiveness is considered to be excellent, which is expressed as "A", and the shear strength ( Peeling strength) when the average is 4.9MPa or more and less than 9.8MPa, it is considered that the resin adhesion is good, expressed as "B", and when the shear strength (peeling strength) is less than 4.9MPa on average, the resin adhesion is considered poor, expressed for "C".

Resin adhesiveness was evaluated by measuring "initial shear strength" and "shear strength after high temperature and high humidity test", respectively. The "shear strength after the high-temperature and high-humidity test" is a value after each test piece was resin-molded and left to stand in an environment with a temperature of 85° C. and a humidity of 85% for 168 hours. In addition, "initial shear strength" is the shear strength immediately after each sample piece was resin-molded (before the high-temperature, high-humidity test).

(Powdering evaluation)

The powder falling property was evaluated visually. The evaluation results are shown in Table 7. It should be noted that for the powder falling properties shown in Table 7, when no powder falling from the surface was confirmed, it was expressed as "A (excellent)", and when powder falling was slightly occurred, it was expressed as "B (good)", and powder falling occurred In many cases, it is expressed as "C (failure)", and "A" and "B" are practical levels.

[Table 6]

[Table 7]

Table 7. Performance evaluation results

According to the evaluation results in Table 7, for any of Examples 1 to 30, both the initial shear strength and the shear strength after the high temperature and high humidity test were "A" or "B", and good resin adhesion was maintained. In addition, the powder falling property is also at the level of "A" or "B", which is available for practical use. On the other hand, the specific surface area of the roughened layer was 550%, which was very large, but the ratio of the maximum width to the minimum width of the protrusions forming the roughened layer was not controlled and was outside the scope of the present invention (5.2) in Comparative Example 1 , although the initial shear strength is "A", the resin adhesion is excellent, but the shear strength after the high temperature and high humidity test becomes "C", and the resin adhesion is greatly deteriorated. In addition, the powder shedding property is also poor, as "C", not a practical level.

Industrial availability

Even when the lead frame material of the present invention is subjected to a high-temperature and high-humidity durability test, such as a high-temperature and high-humidity test in an environment with a temperature of 85°C and a humidity of 85% for 168 hours, it can maintain good resistance to the lead frame. The resin adhesiveness is almost not deteriorated, and the semiconductor package composed of this lead frame material can realize high reliability.

Explanation of reference signs

1 Conductive substrate

2 Coarsening layers

2-1 First roughening layer (the first roughening layer from the substrate side)

2-2 Second roughening layer (second roughening layer from the substrate side)

3,3-1 Coarse coating

4,4-1 Protrusions

10,10A lead frame material

A The length of the section line segment of the outermost surface of the roughened film

B The length of the cross-sectional line segment of the surface of the conductive matrix

Claims (5)

1. A lead frame material comprising: a conductive substrate which is a copper alloy and has a tensile strength of 350-800 N/mm ² , an electrical conductivity of 30-90% IACS, and a thickness of 0.1-2 mm, and a roughened film comprising at least one roughened layer formed by a plurality of protrusions of roughened particles directly or via an intermediate layer on at least one side of the conductive substrate, The roughened layer is made of copper metal or nickel metal, The protrusions have a shape in which the maximum width when measured on a cross-section in the thickness direction of the roughened film is measured relative to the lower portion located closer to the conductive substrate than the measurement position of the maximum width. The minimum width is 1 to 5 times. 2. The lead frame material according to claim 1, further comprising a surface coating comprising at least one surface coating layer on at least a part of the surface of the roughened coating, the surface coating layer comprising a material selected from the group consisting of palladium, , palladium alloy, rhodium, rhodium alloy, ruthenium, ruthenium alloy, platinum, platinum alloy, iridium, iridium alloy, gold, gold alloy, silver and silver alloy. 3. The lead frame material according to claim 1 or 2, wherein the intermediate layer is nickel, nickel alloy, cobalt, cobalt alloy, copper or copper alloy. 4. A method of manufacturing a lead frame material, comprising a step of forming a roughened coating, the roughened coating comprising a plurality of roughened particles formed by electroplating directly or via an intermediate layer on at least one side of a conductive substrate At least one roughening layer formed by protrusions; The conductive matrix is a copper alloy with a tensile strength of 350-800N/mm ² , an electrical conductivity of 30-90% IACS, and a thickness of 0.1-2mm. The roughened layer is made of copper metal or nickel metal, The protrusions have a shape in which the maximum width when measured on a cross-section in the thickness direction of the roughened film is measured relative to a lower portion located closer to the conductive substrate side than the measurement position of the maximum width. The minimum width is 1 to 5 times. 5. A semiconductor package having the lead frame material according to any one of claims 1 to 3.

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